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-rw-r--r--src/libac3/decode.c314
1 files changed, 314 insertions, 0 deletions
diff --git a/src/libac3/decode.c b/src/libac3/decode.c
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+/*
+ * decode.c
+ *
+ * Copyright (C) Aaron Holtzman - May 1999
+ *
+ * This file is part of ac3dec, a free Dolby AC-3 stream decoder.
+ *
+ * ac3dec is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * ac3dec is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Make; see the file COPYING. If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/time.h>
+
+#include "ac3.h"
+#include "ac3_internal.h"
+#include "bitstream.h"
+#include "downmix.h"
+#include "srfft.h"
+#include "imdct.h"
+#include "exponent.h"
+#include "coeff.h"
+#include "bit_allocate.h"
+#include "parse.h"
+#include "crc.h"
+#include "rematrix.h"
+#include "sanity_check.h"
+
+#include "audio_out.h"
+#include "attributes.h"
+
+
+//our global config structure
+ac3_config_t ac3_config;
+#ifdef FAST_ERROR
+jmp_buf error_jmp_mark;
+#else
+uint32_t error_flag = 0;
+#endif
+
+static audblk_t audblk;
+static bsi_t bsi;
+static syncinfo_t syncinfo;
+static uint32_t frame_count = 0;
+static uint32_t is_output_initialized = 0;
+
+//the floating point samples for one audblk
+static stream_samples_t samples;
+
+//the integer samples for the entire frame (with enough space for 2 ch out)
+//if this size change, be sure to change the size when muting
+static int16_t s16_samples[2 * 6 * 256] __attribute__ ((aligned(16)));
+
+/* output buffer for spdiv output */
+static int16_t s16_samples_out[4 * 6 * 256] __attribute__ ((aligned(16)));
+
+static ao_functions_t ac3_output;
+
+// downmix stuff
+static float cmixlev_lut[4] = { 0.707, 0.595, 0.500, 0.707 };
+static float smixlev_lut[4] = { 0.707, 0.500, 0.0 , 0.500 };
+static dm_par_t dm_par;
+
+//Storage for the syncframe
+#define BUFFER_MAX_SIZE 4096
+static uint8_t buffer[BUFFER_MAX_SIZE];
+static uint32_t buffer_size = 0;;
+
+static uint32_t decode_buffer_syncframe (syncinfo_t *syncinfo, uint8_t **start, uint8_t *end)
+{
+ uint8_t *cur = *start;
+ uint16_t syncword = syncinfo->syncword;
+ uint32_t ret = 0;
+
+ //
+ // Find an ac3 sync frame.
+ //
+ while (syncword != 0x0b77) {
+ if (cur >= end)
+ goto done;
+ syncword = (syncword << 8) + *cur++;
+ }
+
+ //need the next 3 bytes to decide how big the frame is
+ while (buffer_size < 3) {
+ if(cur >= end)
+ goto done;
+ buffer[buffer_size++] = *cur++;
+ }
+
+ parse_syncinfo (syncinfo,buffer);
+
+ while (buffer_size < syncinfo->frame_size * 2 - 2) {
+ if(cur >= end)
+ goto done;
+
+ buffer[buffer_size++] = *cur++;
+ }
+
+#if 0
+ // Check the crc over the entire frame
+ crc_init();
+ crc_process_frame (buffer, syncinfo->frame_size * 2 - 2);
+
+ if (!crc_validate()) {
+#ifndef FAST_ERROR
+ error_flag = 1;
+#endif
+ fprintf(stderr,"** CRC failed - skipping frame **\n");
+ goto done;
+ }
+#endif
+
+ //
+ //if we got to this point, we found a valid ac3 frame to decode
+ //
+
+ if ((ac3_config.flags & AO_MODE_AC3) == 0) {
+ bitstream_init (buffer);
+ //get rid of the syncinfo struct as we already parsed it
+ bitstream_get (24);
+ }
+
+ //reset the syncword for next time
+ syncword = 0xffff;
+ buffer_size = 0;
+ ret = 1;
+
+done:
+ syncinfo->syncword = syncword;
+ *start = cur;
+ return ret;
+}
+
+
+void inline decode_mute (void)
+{
+ //mute the frame
+ memset (s16_samples, 0, sizeof(int16_t) * 256 * 2 * 6);
+#ifndef FAST_ERROR
+ error_flag = 0;
+#endif
+}
+
+
+void ac3_init(ac3_config_t *config ,ao_functions_t *foo)
+{
+ memcpy(&ac3_config,config,sizeof(ac3_config_t));
+ ac3_output = *foo;
+
+ imdct_init ();
+ /* downmix_init (); */
+ sanity_check_init (&syncinfo,&bsi,&audblk);
+ memset(s16_samples_out,0,4 * 6 * 256);
+
+}
+
+void ac3_reset ()
+{
+ printf ("ac3_reset\n");
+#ifndef FAST_ERROR
+ error_flag = 0;
+#endif
+
+ frame_count = 0;
+ is_output_initialized = 0;
+
+ buffer_size = 0;
+ syncinfo.syncword = 0;
+ imdct_init();
+ sanity_check_init(&syncinfo,&bsi,&audblk);
+
+}
+
+size_t ac3_decode_data (uint8_t *data_start, uint8_t *data_end, uint32_t pts_)
+{
+ uint32_t i;
+
+#ifdef FAST_ERROR
+ if (setjmp (error_jmp_mark) < 0) {
+ imdct_init ();
+ sanity_check_init(&syncinfo,&bsi,&audblk);
+ return 0;
+ }
+#endif
+
+ while (decode_buffer_syncframe (&syncinfo, &data_start, data_end)) {
+
+#ifndef FAST_ERROR
+ if (error_flag)
+ goto error;
+#endif
+
+ if ((ac3_config.flags & AO_MODE_AC3) == 0) {
+ parse_bsi (&bsi);
+
+ // compute downmix parameters
+ // downmix to two channels for now
+ dm_par.clev = 0.0; dm_par.slev = 0.0; dm_par.unit = 1.0;
+ if (bsi.acmod & 0x1) // have center
+ dm_par.clev = cmixlev_lut[bsi.cmixlev];
+
+ if (bsi.acmod & 0x4) // have surround channels
+ dm_par.slev = smixlev_lut[bsi.surmixlev];
+
+ dm_par.unit /= 1.0 + dm_par.clev + dm_par.slev;
+ dm_par.clev *= dm_par.unit;
+ dm_par.slev *= dm_par.unit;
+
+ for(i=0; i < 6; i++) {
+ //Initialize freq/time sample storage
+ memset (samples, 0, sizeof(float) * 256 * (bsi.nfchans + bsi.lfeon));
+
+ // Extract most of the audblk info from the bitstream
+ // (minus the mantissas
+ parse_audblk (&bsi,&audblk);
+
+ // Take the differential exponent data and turn it into
+ // absolute exponents
+ exponent_unpack (&bsi,&audblk);
+#ifndef FAST_ERROR
+ if (error_flag)
+ goto error;
+#endif
+
+ // Figure out how many bits per mantissa
+ bit_allocate (syncinfo.fscod,&bsi,&audblk);
+
+ // Extract the mantissas from the stream and
+ // generate floating point frequency coefficients
+ coeff_unpack (&bsi,&audblk,samples);
+#ifndef FAST_ERROR
+ if (error_flag)
+ goto error;
+#endif
+
+ if (bsi.acmod == 0x2)
+ rematrix (&audblk,samples);
+
+ // Convert the frequency samples into time samples
+ imdct (&bsi,&audblk,samples, &s16_samples[i * 2 * 256], &dm_par);
+
+ // Downmix into the requested number of channels
+ // and convert floating point to int16_t
+ // downmix(&bsi,samples,&s16_samples[i * 2 * 256]);
+
+ if (sanity_check(&syncinfo,&bsi,&audblk) < 0)
+ sanity_check_init (&syncinfo,&bsi,&audblk);
+
+ continue;
+ }
+ }
+ else {
+ s16_samples_out[0] = 0xf872; //spdif syncword
+ s16_samples_out[1] = 0x4e1f; // .............
+ s16_samples_out[2] = 0x0001; // AC3 data
+ s16_samples_out[3] = syncinfo.frame_size * 16;
+ s16_samples_out[4] = 0x0b77; // AC3 syncwork
+
+ // ac3 seems to be swabbed data
+ swab(buffer,&s16_samples_out[5], syncinfo.frame_size * 2 );
+
+ }
+
+ if (!is_output_initialized) {
+ ac3_output.open (16, syncinfo.sampling_rate,
+ (ac3_config.flags & AO_MODE_AC3) ? AO_MODE_AC3 : AO_MODE_STEREO);
+ is_output_initialized = 1;
+ }
+
+ if ((ac3_config.flags & AO_MODE_AC3) == 0) {
+ ac3_output.write_audio_data(s16_samples, 256*6, pts_);
+ }
+ else {
+ ac3_output.write_audio_data(s16_samples_out, 6 * 256, pts_);
+ }
+
+ pts_ = 0;
+
+#ifndef FAST_ERROR
+error:
+
+ //find a new frame
+ decode_mute (); //RMB CHECK
+#endif
+ }
+#ifdef FAST_ERROR
+ decode_mute ();
+#endif
+
+ return 0;
+}
+
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